class Test{
    String name ;
    int age ;

    @Override
    public String toString() {
        return "test{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

public class Test1 {

    public static void main(String[] args) {
        String a = "abc" ;
        System.out.println(a.toUpperCase() == "ABC");
    }
    public static void main9(String[] args) {
//        String str = String.format("%d:%d",20,30) ;
//        System.out.println(str);
        String str1 ="ababab" ;

//        String str2 = str1.replace('a','n') ;
//        System.out.println(str2);
//
//        String str3 = str1.replace("ab", "66") ;
//        System.out.println(str3);
//         String str4 = str1.replaceFirst("ab", "sb") ;
//        System.out.println(str4);
        String str5 = str1.replaceAll("ab","6") ;
        System.out.println(str5);
    }
    public static void main8(String[] args) {
        String arr = "abcd" ;
        char[] array = arr.toCharArray();
        char[] array2 = {'1','2','3'} ;
        String str = new String(array2) ;


    }
    public static void main7(String[] args) {
        String arr = "abcd" ;
        String ARR = "ABCD" ;
        System.out.println(arr.toUpperCase());
        System.out.println(ARR.toLowerCase());
    }
    public static void main6(String[] args) {
//        String str1 = String.valueOf(1);
//        String str2 = String.valueOf(1.2);
//        String str3 = String.valueOf( true);
//        System.out.println(str1);
//        System.out.println(str2);
//        System.out.println(str3);
//      String str4 = String.valueOf(new Test());
//        System.out.println(str4);
           int a = Integer.parseInt("123") ;
           double b = Double.parseDouble("123.12") ;
        System.out.println(a);
        System.out.println(b);

    }


    public static void main5(String[] args) {
        String str = "abcabcabc" ;
        System.out.println(str.lastIndexOf('b' , 5));
    }
    public static void main4(String[] args) {
        String a = "abcdef" ;
//        System.out.println(a.charAt(1));
        System.out.println(a.indexOf("cd" , 3));

    }
    public static void main3(String[] args) {
        String a = "abc" ;
        String b = "Abc" ;
        System.out.println(a.compareToIgnoreCase(b));

    }
    public static void main1(String[] args) {
//        String a = "123" ;
//        System.out.println(a.length());
//        System.out.println("123".length());
//        String b = "1" ;
//        System.out.println(b.isEmpty());
//        System.out.println("123".isEmpty());
//
//          String c = null ;
//          c.isEmpty() ;
        String a   = new String("123");
        String b = new String("123") ;
        System.out.println(a==b);

        String c = "123" ;
        String d ="123" ;
        System.out.println(c==d);

    }
}
